1. Field of the Invention
The present invention relates to a reduction gear structure applied to a vehicle having dedicated motor units and reduction gear devices for respective driving wheels.
2. Background Art
Conventionally, it is a well-known technique to provide dedicated motor units for respective driving wheels to secure a free space in the central part in the width direction of the vehicle. (See, for example, the specification of the U.S. Pat. No. 6,591,593. Hereinafter referred to as a cited reference.)
Particularly, the cited reference discloses a vehicle including: a pair of main frames; a pair of driving wheels, each of which is supported by each of the pair of main frames, respectively; and a pair of motor units, each of which drives each of the pair of driving wheels, respectively, in which a free space is secured between the pair of driving wheels.
In addition to the aforementioned configuration, the vehicle described in the cited reference further include a reduction device disposed between each of the pair of motor units and the driving wheel corresponding thereto, respectively.
With such reduction devices, a motor unit of a high-speed output type can be used, whereby torque for operating the motor units can be reduced.
In a vehicle in which a dedicated motor unit is provided for each driving wheel, a brake mechanism must be provided for each driving wheel. In other words, a dedicated brake mechanism must be provided between a motor unit and a driving wheel operatively driven by the motor unit. However, the cited reference does not clearly disclose this aspect.
Further, it is ideal for vehicle manufacturers that consideration has been made to enable motor units and reduction devices to be mounted without any limitation due to the dimensions and the shape of the main frames, and it is also desirable to easily complete such mounting operations. However, the cited reference does not clearly disclose these aspects as well.